How Many Bags of Concrete for a 10x10 Slab? (4-Inch & 6-Inch)

Short answer: A 10 × 10 ft slab poured 4 inches thick needs 1.23 cubic yards of concrete. With the standard 10% extra, that's about 62 bags of 80-lb concrete or 82 bags of 60-lb concrete, or 1.36 cubic yards if you order ready-mix.

At 6 inches thick, the same slab needs about 92 bags of 80-lb concrete (2.04 cubic yards of ready-mix).

The Math, Step by Step

Concrete is ordered by volume, so start with cubic feet.

1. Area: 10 ft × 10 ft = 100 sq ft
2. Thickness in feet: 4 inches ÷ 12 = 0.333 ft
3. Volume: 100 × 0.333 = 33.3 cubic feet
4. Cubic yards: 33.3 ÷ 27 = 1.23 cubic yards
5. Add 10% extra for uneven ground, spillage, and form flex: 33.3 × 1.10 = 36.7 cubic feet

Then divide by what one bag yields:

Concrete Chart for Common Slab Sizes

Every number includes 10% extra, using the same method as our concrete calculator. All slabs are 4 inches thick unless noted.

4 Inches or 6 Inches?

• 4 inches is standard for patios, walkways, shed floors, and hot tub pads that don't carry vehicles.
• 5 to 6 inches is the norm for driveways, parking pads, and anything that will hold a car or heavy equipment.

Local building codes can set minimums, so check before you pour anything structural.

Bags or Ready-Mix? Be Honest About the Work

Sixty-two 80-lb bags is almost 5,000 pounds of concrete to lift, dump, mix, and place, all before the first batch starts to set. That's a big day even with a rented mixer and a helper.

Bagged concrete makes sense when:

• The project is under about 1 cubic yard (an 8×8 slab or smaller)
• You can't get a truck close to the site
• You're pouring in sections, like fence post holes

Ready-mix makes sense when:

• You need more than about 1 cubic yard
• You want one continuous pour with no cold joints
• You'd rather spend the day finishing than mixing

Many suppliers charge a short-load fee for small orders, so a 1.36-yard delivery can cost about the same as the bags plus mixer rental. Get a quote for both.

Prep Makes or Breaks a Slab

The concrete is only as good as what's under it:

1. Dig out the area to allow for 4 inches of gravel plus your slab thickness.
2. Compact a gravel base (about 4 inches) with a plate compactor. Soft soil causes cracks.
3. Build forms from straight 2x4s (for a 4" slab), staked every 3 to 4 feet, with a slight slope away from the house (about 1/8" per foot).
4. Add reinforcement: welded wire mesh or rebar, raised on chairs so it ends up in the middle of the slab, not the bottom.
5. Plan control joints every 8 to 10 feet so the slab cracks where you want it to. A 10×10 slab gets one joint each way through the middle.

Tools for a Bagged Concrete Pour

The Bottom Line

For a 10 × 10 ft concrete slab:

• 4 inches thick: 1.23 yd³ → about 62 bags (80 lb) or 1.36 yd³ ready-mix with extra
• 6 inches thick: 1.85 yd³ → about 92 bags (80 lb) or 2.04 yd³ ready-mix with extra
• Over about 1 cubic yard, price out ready-mix before committing to bags

Have a different size, a footing, or post holes? The free concrete calculator handles slabs, footings, columns, and stairs.